Resolving dependencies...
cabal: Could not resolve dependencies:
next goal: extcore (user goal)
rejecting: extcore-1.0.2, extcore-1.0.1, extcore-1.0, extcore-0.9.2,
extcore-0.9.1, extcore-0.9, extcore-0.8, extcore-0.7, extcore-0.6,
extcore-0.5, extcore-0.4, extcore-0.3 (constraint from user target requires
==0.2)
trying: extcore-0.2
next goal: base (dependency of extcore-0.2)
rejecting: base-4.9.0.0/installed-4.9... (conflict: extcore => base>=3 && <=4)
rejecting: base-4.9.0.0, base-4.8.2.0, base-4.8.1.0, base-4.8.0.0,
base-4.7.0.2, base-4.7.0.1, base-4.7.0.0, base-4.6.0.1, base-4.6.0.0,
base-4.5.1.0, base-4.5.0.0, base-4.4.1.0, base-4.4.0.0, base-4.3.1.0,
base-4.3.0.0, base-4.2.0.2, base-4.2.0.1, base-4.2.0.0, base-4.1.0.0,
base-4.0.0.0, base-3.0.3.2, base-3.0.3.1 (constraint from non-upgradeable
package requires installed instance)
Dependency tree exhaustively searched.